(1) Field of the Invention
The present invention relates to a casting installation for liquid metal and notably to a ladle shroud that can be introduced into such an installation.
(2) Description of the Related Art
A ladle shroud is a tube comprising a canal extending essentially along an axis; the canal allowing the liquid metal from a metallurgical container, such as a ladle, to pass to a tundish. Such a tube is introduced into the installation in such a way that the axis of the canal is vertical and that the upper end thereof is in contact with an upstream element of the installation, while the lower end thereof is immersed in the tundish.
A ladle shroud comprising, at an end portion of the shroud corresponding to an upper end portion of the canal, a metallic jacket framing a tube body is known from the prior art and this metallic jacket is of a thickness less than or equal to 5 millimeters. Such a jacket, because of its small size, serves only to reduce the inevitable dimensional tolerances that arise when manufacturing the shroud made of refractory material. In particular, such a jacket is entirely incompatible with the stress loadings (temperature, pressure) associated with the use of the shroud and, therefore, it is impossible to conceive of using this jacket to hold or position the ladle shroud. These problems are further exacerbated if there is a desire to use such shrouds in a device for introducing ladle shrouds by sliding because in such a case the loadings (tensile stress loadings for example) are even more localized than they are in a conventional push-fit device.
Before introducing the shroud into the installation, the end portion of the shroud may be fitted into a removable stiffening frame (see, for example, WO-A1-2004/052576). This frame is then placed on a support and the shroud and frame assembly is introduced into the casting installation so that the end portion of the shroud is in contact with the upstream element of the casting installation.
The fitting of such a frame is a fairly length and relatively complex operation for the operator to perform. Such a frame is also extremely expensive. There is therefore a need to simplify the operations in the casting installation, notably in order to reduce the costs associated with casting.